Jpod101 has a word of the day feature, which is very nice, but I believe it can do better with a proverb of the day as well.
I got this idea recently when visiting another learning site. Unfortunately, most sites don't offer native audio to play the pronunciation of words as Jpod101 does.
Learning proverbs offer a glimpse of culture, provide memorable key phrases, and are just good lessons in general. It is also an avenue by which foreign language learners learn to think like native speakers of the language. After all, with easily memorable phrases, grammar will naturally transfer like osmosis rather than as a strict set of guidelines.
Sorry another edit: another reason - to add on to thinking like native speakers of the language, it also entails thinking less literally of the words and more figuratively. Perhaps teaching a proverb a day may require an actual lesson write-up, in which case it is not that convenient. But if that is the case, I strongly suggest more proverb lessons!